Method of producing flush contacts



July 18, 1944.

H. KERSHAW METHOD OF PRODUCING FLUSH CONTACTS Filed Feb. ll, 1945 2 Sheets-Sheet l Henry grslkam @gw am,

July 18, 1944.

Hmry Mrs/Law.

GMM/Man Patented July 18, 1944 UNITED STATES PATENT OFFICE METHOD F PRODUCING FLUSH CONTACTS Henry Kershaw, Belleville, N. J.

Application February 11, 1943, Serial No'. 475,538

4 Claims.

My invention relates to a method of producing metal iiush contactsV or the like, and for securing the same to metal elements.

As is welll known, metal flush contacts are made from a solid cylindrical metal blank. This metal blank is placed in a screw machine and the blank is cut to produce the flush contact. This flush contact includes a cylindrical head having an integral shank and a base-disc integral with the shank. This lbase-disc is subsequently welded to a metallic element' or disc of electrical apparatus, such as a radio tube. This operation is timeconsuming and expensive.

An important object of the invention is to provide a method whereby the flush contacts can be produced in succession from, a metal wire or rod and weldedV to the desired metallic elements.

A further object of the invention is to provide a method for forming flush contacts upon a metal wire or rod, and weld each ilush contact to the desired metallic element, and then sever the welded flushcontact from the wire or rod.

A further object of the invention is to subject the metal wire or rod to the action of an electric current, at a point remote from the free end of the wire, to plasticize the wire, and then form the plasticized metal into the head, having a transverse dimension greatery than that of the wire and retaining the head integral with the wire.

A further object of the method is to retain the continuity of the wire during the formation of the ush contacts, so that the wire may be properly fed.

A further object of the invention is to provide a method of the above mentioned character, which will exert a pull upon the flush contact after it is welded to the metallic element, to test the strength oi the weld, prior to severing the attached flush contact from the wire.

A further object of the` invention is to provide a method of the above mentioned character which is continuous in operation and will have a large output, thereby reducing the cost of producing flush contacts and the securing of the same to the metal elements.

A further object of the method is to produce a nished flush contact and to secure the same to a desired metallic element by welding.

Other objects and advantages of the invention will be apparent during the course of the following description.

In the accompanying drawings forming a part of this application and in which like numerals are employed to designate like parts throughout the same,

Figure 1 is aside elevation of apparatus embodying my invention, showing the wire moved to bring its leading end into contact with the metallic element, the yblades and the jaws being in the open position and the upper heating and forming jaws elevated,

Figure 2 is a central vertical longitudinal section through the. apparatus, the elements being arranged in the same positions,

Figure 3 is a similar view showing the jaws moved to the inner position, the upper heating and forming jaws elevated, and the blades in the open position,

Figure 4 isa similar view, with the upper heating and forming jaws moved to the lowered position, and the blades in the open position,

Figure 5 isy a fragmentary plan view of the guide means for the metallic elements,

Figure 6 is a transverse section taken on line 6--6-of Figure 5,

Figure 'l is a similar view taken on line 'I--T of Figure 5,

Figure 8` is an inner end elevation of the heating and forming jaws and the cold clamping jaws,

Figure 9' is a` diagrammatic view showing the circuit connected with the heating and forming jaws,

Figure l0 is a diagrammatic View showing the welding circuit, and,

Figure` 11 is a perspective view of the completed flush contact welded to the metallic element.

In ther drawings, wherein for the purpose of illustration is shownl a preferred embodiment of apparatus for the practice of the method, the numeral IIJ designates abase, having guide means II to receive metallic elements or discs I2. The guide means has inwardly projecting horizontal angesl 4, engaging all of the top anges I5 of the element I2, to hold the element against upward vertical movement, when the wire is pulled to test the weld.

At.A the welding. position, the guide means II is cut away so that it does not support the element I2, and at this position, the base. I0 has an opening I6, to receive a stationary insulating plug Il, receiving a vertically slidable metallic pin I8, carried by a metallic disc I9. The numeral 2B designates a pneumatic cell, which is inil'ated to the desired pressure. The pin I8 and the disc I9 are light and when the welding between the flush contact and the metallic element occurs, the resilient action of the cell 20' causes the cell to `the shape and size of the metallic elements.

carry through instantly, without loss of time due to inertia, whereby the contacting parts being welded are instantly brought together.

The metallic elements l2 are preferably fed longitudinally through `the guide means by any 2,316,597, under date of April 13, 1943, for Method f of and apparatus for welding. This lmeans would have to be slightly modified to accommodate Any other means may be employed or each metallic `element may be manually moved to the welding position and placed upon the pin I8.

Arranged near and above the base are horizontal reciprocatory blades 2|, operating in xed guides and having upper beveled faces 22. These blades are moved inwardly and sever the wire 23 and produce a tapered end 23, to increase the resistance when such tapered end is brought into contact with the metallic element. Anysuitable means may be employed to move the blades, in timed order, to opened and closed positions, including cams.

Arranged near and above the blades 2| is a lower pair of cold forming jaws 24, preferably formed of metal. These cold forming jaws are horizontal and reciprocate to opened and closed gpositions. The jaws 24 may be water cooled. Any xed means are employed to support and guide the lower cold forming jaws 24 so that they travel in a straight path, and any suitable means may be used to reciprocate them in timed order, including cams and the like. The jaws 24 have their inner opposed ends provided with semispherical recesses 25 and semi-cylindrical grooves 26 above and below the recesses.

Rigidly mounted upon the cold forming jaws 24 are heating and forming jaws 21, electrically insulated therefrom, as shown at 28. The lower pair of heating and forming jaws is preferably formed of carbon. Vertical guide pins 29 are rigidly secured to the lower cold forming jaws 24 and extend upwardly above the jaws 24 and pass through openings 30 formed in the jaws 21 and in an upper pair of heating and forming jaws 3|, preferably formed of carbon. These guide pins also pass into openings 33a formed in upper cold clamping metallic jaws 34. The guide pins 2S carry springs 32, which are insulated from the jaws 21 and 3|, and serve to elevate the jaws 3|. The upper cold clamping metallic jaws 34 are rigidly mounted upon the jaws 3| and electrically insulated from the jaws 3|. The extent of upward movement of the jaws 3| and 34 is limited by adjustable nuts 32', carried by vertical pins 33, and locked in the selected adjusted position by lock nuts 34. The vertical pins 33 are rigidly secured to the jaws 24 and pass through large openings 33b in the jaws 21 and 3| and are insulated from these jaws.

The upper cold clamping metallic jaws 34 are rigidly secured to and insulated from the jaws 3|, as stated. These jaws 34 have openings 33C, slidably receiving the pins 33. The jaws 34 may be formed of metal and may be water cooled. The jaws 34' have vertical semi-cylindrical grooves 35 to receive and hold the wire 23. It

is thus seen that each vertical set of jaws 2l, 21, 3| and 34' will reciprocate horizontally as a unit, while the upper heating and forming `jaws 3| and the cold clamping jaws 34 are shiftable vertically toward and from the heating and forming jaws 21. Any suitable means may be provided to reciprocate the jaws 24, in proper timed order, and all jaws carried thereby are accordingly reciprocated. The lower heating and forming jaws are provided at their inner opposed ends with quarter-spherical ,recesses and vertical semi-cylindrical grooves 36 beneath the same. The upper heating and forming jaws 3| are provided at their inner opposed end with quarterspherical recesses 31 and vertical semi-cylindrical grooves 38 above the same. When the upper heating and forming jaw 3| is moved downwardly to contact with the lower heating and forming jaw 21, recesses 35 and 31 are combined to form a semi-spherical recess. The grooves 35, 38, 36, and 25 have the same radii. The recesses 31, 35' and 25 preferably have the same radii although I contemplate having the radius of the recess 25 slightly smaller than the radius of the recesses 31 and 35.

Means are provided to depress the upper heating and forming jaws 3| including horizontal reciprocatory bars 39, moved inwardly and outwardly in timed order by any suitable means including cams or the like. These bars 39 slide in fixed horizontal guides and carry rollers 40, engaging within recesses 4|, having inclined inner ends 42. When the rollers 40 are within the recesses 4| they do not depress the jaws 3|, upon the inward or outward movement of the jaws, but when the rollers 40 are moved inwardly With respect to the jaws 3| so that they ride upon the inclined ends 42, they depress the jaws 3|, Figure 4.

Means are provided to effect an intermittent stey-by-step downward movement of the Wire 23' and the length of each step defines the length of the flush contact produced. This Wire feeding means may be of any suitable form, but I prefer to employ substantially the wire feeding means shown in my said copending application, Serial No. 420,876. This wire feeding means comprises generally a vertically reciprocatory slide 43, carrying a fiber strip 44 and an opposed metal strip 45, formed of copper or the like and having a guide groove 46 to partly receive the wire. When the slide 43 is moved downwardly the ber strip is forced into clamping engagement with the wire so that the wire is positively gripped and fed a step defined by the downward step of the slide. When the slide moves upwardly, the fiber strip does not have clamping engagement with the wire but does have sufiicient frictional engagement therewith to exert a pull upon the Wire to test the strength of the weld produced between the wire and the metallic element. After the slide has reached the uppermost position, and after the strength of the weld has been tested, the wire is severed.

The pairs of jaws 21 and 3| are connected with the opposite poles of a welding circuit 41.

The metallic jaw 35 is connected with one pole of a welding circuit 48 and the metallic pin I8 is connected with the opposite pole of the same circuit.

The practice of the method is as follows:

The metal wire or rod 23 vmay be stainless steel and may have a diameter of eighty thousandths of an inch (.080"), andA is paid out from a spool and is fed vertically and downwardly between the jaws 44 and 45. The slide 43 moves downwardly while all of the remaining jaws and the blades are in the open position. The wire is thereby passed and guided between the jaws 34',

3|, 21 and 24 and in alignment with the vertical grooves of the saine. The slide stops in the lowered position and the leading end of the wire is brought into contact with the metallic element I2. The jaws 34', 3l, 2l' and 24 are now moved inwardly and grip the wire 23', while the upper jaws 3l are elevated. The cylindrical recesses produced by the assembled semi-cylindrical grooves 26, 3B, 33 and 35 have a slightly smaller diameter than the wire 23 so that the several horizontal jaws have a suitable clamping engagement with the wire. The diameter of the cylindrical recesses may be from one thousandth of an inch (.001) to two thousandths of anfinch (.002") smaller than the diameter of the wire, while these dimensions may be varied.

The degree of pressure that the horizontal jaws exert upon the wire may be regulated and the pressure may be yieldingly applied, if desired. There must be considerable pressure so that the jaws will have clamping engagement with the wire so that the wire is held against the possi bility of slipping with relation to the jaws. When the horizontal jaws are moved inwardly, the cold clamping jaws have clamping engage-ment with the wire and will move the adjacent portion of the wire downwardly toward its leading end when the jaws 3l and 3s are depressed, while the cold forming jaws 2a have clamping engage ment with the wire and the previously :formed head to hold the adjacent portion of wire against downward movement toward its leading end. When the jaws 2 and SI are shifted inwardly and the jaws 3l moved downwardly, the circuit 41 is now closed, .and retained closed for a suiiicient length of time to plasticze that portion of the wire engaged by the jaws 3l and 21 and arranged between the jaws Sil and 2, The maximum plasticizing action rst occurs at the line of contact between the walls lof the grooves 36 and 38 and wire. As soon` as the plasticizing action is started, the rollers are moved ir1- wardly and depress the upper jaws 3i, as the plasticizing action progresses, the clamping jaws 34 rigidly gripping the wire and feeding the saine through the wire feed means, The portion. of the wire between the recesses 35 and 31 is thereby brought into contact with the walls of the recesses as the recesses 31 move toward the recesses 35', and the plasticizing action increases, between the points A, and about the time that the recesses 31 are moved down to the completely closed position and the close-d spherical recess is produced, the plasticizing may be comi pleted or substantially completed, and the closed recess will then form the spherical head B upon the wire. This head is of course integral with the wire. As soon as this occurs the welding or melting circuit is opened and all horizontal jaws are then shifted to the outer position, which occurs after the formed head and adjacent portions of the wire have frozen or become solid, these portions `freely separating from the jaws 3| and 21. It is thus seen that the wire is gripped and held against movement near its leading end and gripped at a point spaced from its leading end and the intermediate portion of the wire between these gripped portions is heated and plasticized, at about which time the trailing gripped portion of the wire is moved longitudinally toward the gripped leading portion, whereby the intermediate f the wire to the element I2.

plasticized portion of the wire is forced into lthe forming recess. This forms a spherical head having a greater diameter than the wire, andintegral therewith. After the head is thus formed from the wire and is rendered solid, and the horizontal jaws shifted to the opened position, theslideis returned to the upper position, as will be further explained. While all horizontal jaws are open,

and the slide 43 elevated, the slide 43 again movesy downwardly and advances the wire for the next step, bringing the leading head B opposite to and in alignment with the semispherical recesses 25. The slide remains in the lowered position. `All jaws `again move inwardly tothe closed position while the upper jaws SI remain elevated. The welding or heating circuit connected with the jaws 21 and 3i is again closed, and the intermediate portion of the wire is plasticized, and the upper jaws 3| are again depressed and iorce'the plasticized portion of the wire into the closed spherical recess, forming the next spherical head B. At this time, the leading spherical head B is held within the spherical, recess produced by the semispherical recesses 25 and this head is coldpressed, thereby further forming the same. The cycle of operation is repeated and spherical heads are formed upon the wire 23 in succession at equi-distantly spaced points. Upon each downward movement of the slide t3, the leading end of the wire beneath the leading head B is brought into firm contact with the metallic element I2, and when all horizontal jaws are moved inwardly the welding circuit connected with the jaw 45 and pin I8 is closed to weld the leading end of The wire 23' depresses the metallic element I2 and the cell 2l) is compressed, which occurs before the horizontal jaws are moved inwardly. The resilient action of the cell 2i) follows through instantly without loss of time clue to inertia, to efect a proper weld. This welding circuit is opened when the weld .is completed. While the welding of the leading end of the wire to the metallic element may occur while the horizontal jaws are closed, it may also occur as soon as the wire is brought down to contact with the metallic element, and before the jaws close. When the horizontal jaws open and after the weld has frozen or hardened, the slide 43 moves upwardly and exerts a pull upon the wire to test the strength of the weld.v After this pulling action and when the horizontal are opened, the blades ZI move inwardly and sever the wire above and adjacent to the head B, and these blades produce the tapered end upon the leading end of the wire. The severing oi the wire upon that side of the head remote from the leading end of the wire produces the finished flush contact which is welded to the metallic element I2. This flush contact includes the head B and shank C. The tapered end of the shank spreads or flattens out during the welding step, as shown at D.

The line of metallic elements I2 is then fed a step and the completed element I2 with the llush contact welded thereto drops or is removed from the line and the next element I2 is brought to the welding position and the cycle of operation is repeated.

As stated, the wire may have a diameter of eighty thousandths of an inch (.080). The shank C of the ush contact would then have a diameter of eighty thousandths of an inch .080) or slightly less. The head B of the flush contact may have a radius of five hundred and sixty-five ten thousandths of an inch (.0565) and the assembled recesses and 3l produce a spherical recess of the same radius as that stated in connection with the head B or slightly smaller, such as from one thousandth of an inch (.001") to tWo thousandths of an inch (.002") smaller.

It is to be understood that the forms of my invention herein shown and described are to be taken as preferred examples of the same and that various changes in the order of the steps of the method may be resorted to, and that changes in the shape, size and arrangement of parts of the apparatus may also be resorted to Without departing from the spirit of the invention or the scope of the subjoined claims.

Having thus described my invention, what I claim is:

l. The method of forming a ilush Contact attached to a metallic element, comprising feeding a metallic wire longitudinally to bring its leading end into contact with the metallic element, then holding the wire against longitudinal movement, heating the wire at a point remote from the leading end of the Wire to plastcize the same While the wire is so held against longitudinal movement, forming the plasticized portion of the Wire` into a head having a greater diameter than the wire While the wire is so held against longitudinal movement, heating the contacting leading end of the wire and the metallic element to plasticize the same while the Wire is so held against longitudinal movement, moving the metallic element toward the leading plasticized end of the Wire While the Wire is so held against longitudinal movement to Weld the same, and severing the Wire upon that side of the head remote from the leading end.

2. The method of forming a flush Contact attached to a metallic element, comprising supporting the metallic element and applying a force to the same to move it in one direction, feeding a metal Wire longitudinally to bring its leading end into contact with the metallic element and shift the metallic element in opposition to said force so that the force will move the metallic element toward the leading end of the wire when the leading end is plasticized, then holding the Wire against longitudinal movement, heating the Wire at a point remote from the leading end of the wire to plasticize the same while the wir@ is so held against longitudinal movement, moving that portion of the wire next to the plasticized portion and remote from the leading end of the wire longitudinally toward such leading end and forming the plasticized portion into a head having a greater diameter than the wire While the wire is so held against longitudinal movement, heating the contacting leading end of the wire and the metallic element to plasticize the same while the Wire is so held against longitudinal movement, the metallic element moving toward the leading end of the wire when such leading end is plasticized to Weld the same, and severing the wire upon that side of the head remote from the leading end.

3. The method of forming a llush contact at tached to a metallic element, comprising feeding a metallic Wire longitudinally in a succession of steps and holding the wire against longitudinal movement between each successive pair of steps, bringing the leading end of the Wire at the end of each step into contact with a metallic element, applying a force to the metallic element to move it toward the leading end of the wire when such leading end is plasticized, heating the wire at a point remote from its leading end and at the end of such step and while the wire is so held against longitudinal movement to plasticize the same, forming each plasticized portion into a head having a greater diameter than the wire while the wire is so held against longitudinal movement, heating the contacting leading end of the wire and metallic element at the end of each step to plasticize such leading end, the force applied to the metallic element moving the metallic element toward the leading end when the leading end is plasticized to Weld the same, and severing the wire at the end of each step adjacent to the head and upon that side of the head remote from the leading end.

4. The method of forming a flush contact attached to a metallic element, comprising feeding a metallic wire longitudinally in a succession of steps, bringing the leading end of the Wire at the end of each step into contact with a metallic element, applying a force to the metallic element to move it toward the leading end of the Wire when such leading end is plasticized, heating the wire at a point remote from its leading end and at the end of each step to plasticize the same, forming each plasticized portion into a head having a greater diameter than the wire, cold forming each previously formed head at the end of each step and thereby holding the Wire against longitudinal movement at the end of each step, heating the contacting leading end of the wire and metallic element at the end of each step to plasticize such leading end, the force applied to the metallic element moving the metallic element toward the leading end when the leading end is plasticized to weld the same, and severing the wire at the end of each step adjacent to the head and upon that side of the head remote from the leading end.

HENRY KERSHAW. 

